Method for the preparation of a poly(arylene ether)-polyolefin composition, and composition prepared thereby

ABSTRACT

A poly(arylene ether)-polyolefin composition is prepared by melt-blending a poly(arylene ether), a poly(alkenyl aromatic) resin, a hydrogenated block copolymer of an alkenyl aromatic compound and a conjugated diene, and an unhydrogenated block copolymer of an alkenyl aromatic compound and a conjugated diene to form a first blend, and melt-blending the first blend and a polyolefin and additional hydrogenated block copolymer to form a second blend. A reinforcing filler and/or an ethylene/alpha-olefin elastomeric copolymer may, optionally, be added during formation of the second blend or in an additional step. Multiple mixing elements, low throughput, and high extruder rotations per minute may be used to achieve high energy mixing of the first and second blends. Compositions prepared by the method exhibit an improved balance of impact strength, stiffness, and heat resistance, as well as reduced variability of physical properties.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. application Ser. No.09/682,929, flied Nov. 1, 2001, now U.S. Pat. No. 6,627,701 which claimsthe benefit of U.S. Provisional Application Ser. No. 60/258,894, filedDec. 28, 2000.

BACKGROUND

Poly(arylene ether)-polyolefin compositions are well known. Manyreferences teach the desirability of preparing these compositions bycombining all components in a single mixing step. See, for example, U.S.Pat. No. 4,764,559 to Yamauchi et al.; U.S. Pat. No. 4,772,657 toAkiyama et al.; U.S. Pat. No. 4,863,997 to Shibuya et al.; U.S. Pat. No.4,985,495 to Nishio et al.; U.S. Pat. No. 4,990,558 to DeNicola, Jr. etal.; U.S. Pat. Nos. 5,071,912, 5,075,376, 5,132,363, 5,159,004,5,182,151, and 5,206,281 to Furuta et al.; U.S. Pat. No. 5,418,287 toTanaka et al., and European Patent Application No. 412,787 A2 to Furutaet al.

Alternatively, some references teach the desirability of addingcomponents in order of higher to lower viscosities. See, for example,U.S. Pat. Nos. 4,764,559 to Yamauchi et al., U.S. Pat. No. 4,985,495 toNishio et al., and U.S. Pat. No. 5,418,287 to Tanaka et al.

In yet another proposed blending method, a polyphenylene ether and apolypropylene-graft-polystyrene copolymer, with or without unmodifiedpolypropylene, are pre-mixed before one or more rubbery substances areadded with additional mixing. See, for example, U.S. Pat. Nos.5,071,912, 5,075,376, 5,132,363, 5,159,004, 5,182,151, and 5,206,281 toFuruta et al.; European Patent Application No. 412,787 A2 to Furuta etal.; and Japanese Unexamined Patent Application 63[1988]-113049 toShibuya et al.

The above-described methods produce compositions that are inadequate formany commercial uses because they exhibit excessive variability in keyproperties, including stiffness and impact strength. There remains aneed for a method of producing poly(arylene ether)-polyolefincompositions having improved property balances. In particular, thereremains a need for a method of producing poly(arylene ether)-polyolefincompositions exhibiting reduced property variability and improvedtradeoffs between stiffness, impact strength, and heat resistance.

BRIEF SUMMARY

The above described and other drawbacks and disadvantages of the priorart are alleviated by a method of preparing a thermoplastic composition,comprising: melt-blending to form a first intimate blend comprising apoly(arylene ether), a poly(alkenyl aromatic) resin, a hydrogenatedblock copolymer of an alkenyl aromatic compound and a conjugated diene;and an unhydrogenated block copolymer of an alkenyl aromatic compoundand a conjugated diene; and melt-blending to form a second intimateblend comprising the first intimate blend, and a polyolefin.

Another embodiment is a method of preparing a thermoplastic composition,comprising: melt-blending to form a first intimate blend comprising apoly(arylene ether), a poly(alkenyl aromatic) resin, a hydrogenatedblock copolymer of an alkenyl aromatic compound and a conjugated diene;and an unhydrogenated block copolymer of an alkenyl aromatic compoundand a conjugated diene; and melt-blending to form a second intimateblend comprising the first intimate blend, a polyolefin, and additionalhydrogenated block copolymer.

Additional embodiments are described in detail below.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a diagrammatic view of kneading blocks used in high and lowintensity upstream and downstream kneading.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment is a method comprising: melt-blending to form a firstintimate blend comprising a poly(arylene ether), a poly(alkenylaromatic) resin, a hydrogenated block copolymer of an alkenyl aromaticcompound and a conjugated diene; and an unhydrogenated block copolymerof an alkenyl aromatic compound and a conjugated diene; andmelt-blending to form a second intimate blend comprising the firstintimate blend, and a polyolefin.

Extensive experiments by the present inventors have led to thesurprising observation that the properties of the composition preparedaccording to this method are substantially and unexpectedly improvedcompared to compositions prepared by known methods, especially thosemethods in which all components are blended simultaneously.

In a preferred embodiment, melt-blending to form the first intimateblend comprises high-energy mixing. The energy of mixing may beexpressed in various ways. One factor contributing to the energy ofmixing is the extruder addition point. For example, when the compositionis compounded on an eleven barrel twin-screw extruder, high-energymixing of the first-intimate blend may be expressed as addition of firstintimate blend components to one of the first four barrels.

Another factor contributing to the energy of mixing is the number ofmixing sections, with greater numbers of mixing sections correspondingto higher energy mixing. Each mixing section may comprise at least onemixing element. The first intimate blend and the second intimate blendare each preferably formed using at least one mixing section. Mixingsections and mixing elements are generally well known in the art ascomponents of twin-screw extruders. Each mixing element is disposednon-rotatably on a screw shaft and is used to disperse and distributecomponents of a thermoplastic composition throughout the blend. Themixing element may or may not advance the composition toward the outletof the extruder. The present inventors have found that the properties ofthe composition are improved if the processes of mixing to form thefirst intimate blend and the second intimate blend each employ at leastone mixing section. In a preferred embodiment, mixing to form the firstintimate blend and the second intimate blend each employ at least twomixing elements on each screw shaft.

There is no particular limitation on the design of the individual mixingelements. Suitable mixing elements include, for example, mixing elementson each of said shafts which are in radial interwiping relation withinthe extruder barrel and configured to wipe one another and the cylinderwalls, as described in U.S. Pat. No. 4,752,135; mixing element diskshaving mixing wings as described in U.S. Pat. Nos. 3,195,868 to Loomanset al. and 5,593,227 to Scheuring et al.; mixing elements having twoopposing lobes wherein one lobe is tapered, as described in U.S. Pat.No. 6,116,770 to Kiani et al.; and the various mixing elements,including those characterized as prior art mixing elements, described inU.S. Pat. No. 5,932,159 to Rauwendaal.

In one embodiment, melt-blending to form a first intimate blend andmelt-blending to form a second intimate blend collectively comprisemixing with a mixing energy input of at least about 0.20kilowatt-hour/kilogram (kW-hr/kg). A mixing energy input of at leastabout 0.22 kW-hr/kg may be preferred, and an energy input of at leastabout 0.24 kW-hr/kg may be more preferred. Such quantitative mixingenergy input may be determined by measuring the rotation rate of theextruder motor and the extruder motor's current draw. Since a directcurrent (DC) motor speed is directly proportional to the voltageapplied, a previously measured proportionality constant may be used toconvert the measured motor speed, in rpm, to a voltage in volts. Theenergy input may then be calculated as the product of the extruder motorcurrent and voltage, divided by the extruder throughput rate. Forexample, an extruder operating at 120 volts, 2 amps, and a throughput of1 kg/hr has an energy input of(120 V)(2 A)/(1 kg/hr)=240 W-hr/kgor 0.240 kW-hr/kg.

In one embodiment, the first intimate blend may be formed and pelletizedin one step, then mixed with the polyolefin to form the second intimateblend in another step.

Suitable temperatures for forming the composition are generally about80° C. to about 400° C. Within this range it may be preferred to formthe first intimate blend by exposing the first intimate blend componentsto a temperature of at least about 200° C., more preferably at leastabout 250° C., yet more preferably at least about 280° C. Also withinthe above range, it may be preferred to form the first intimate blend byexposing the first intimate blend components to a temperature of up toabout 320° C., more preferably up to about 300° C., yet more preferablyup to about 290° C. The same temperatures are also suitable forformation of the second intimate blend.

The method is suitable for preparing the poly(arylene ether)-polyolefincompositions on any scale, from grams to tons. For economical productionof commercially significant amounts of the composition, it may preferredthat the method have a throughput rate of at least about 10 kilogramsper hour (kg/h), more preferably at least about 5,000 kg/h, based on thetotal weight of the composition. Throughput rates of 100,000 kg/h andhigher may be used.

Any known apparatus may be used to carry out the method. Utilization ofthe method on a laboratory scale may employ a lab-scale mixer such as,for example, a Labo Plastomill available from Toyo Seiki Company, Hyogo,Japan. Preferred apparatuses for conducting the method on a larger scaleinclude single-screw and twin-screw extruders, with twin-screw extrudersbeing more preferred. Extruders for melt blending of thermoplastics arecommercially available from, for example, Krupp Werner & PfleidererCorporation (now known as Coperion), Ramsey, N.J. The method may also becarried out using apparatus designed to compound the composition andmold it directly, without an intermediate pelletizing step. Suchapparatus is described, for example, in U.S. Pat. No. 6,109,910 toSekido, and U.S. Pat. No. 6,464,910 B1 to Smorgon et al; U.S. patentapplication Ser. No. 2003/0021860 A1 to Clock et al; and InternationalPublication No. WO 02/43943 A1 to Adedeji et al.

The first intimate blend may comprise any conventional poly(aryleneether). The term poly(arylene ether) includes polyphenylene ether (PPE)and poly(arylene ether) copolymers; graft copolymers; poly(aryleneether) ether ionomers; and block copolymers of alkenyl aromaticcompounds, vinyl aromatic compounds, and poly(arylene ether), and thelike; and combinations comprising at least one of the foregoing; and thelike. Poly(arylene ether)s are known polymers comprising a plurality ofstructural units of the formula:

wherein for each structural unit, each Q¹ is independently halogen,primary or secondary C₁-C₈ alkyl, phenyl, C₁-C₈ haloalkyl, C₁-C₈aminoalkyl, C₁-C₈ hydrocarbonoxy, or C₂-C₈ halohydrocarbonoxy wherein atleast two carbon atoms separate the halogen and oxygen atoms; and eachQ² is independently hydrogen, halogen, primary or secondary C₁-C₈ alkyl,phenyl, C₁-C₈ haloalkyl, C₁-C₈ aminoalkyl, C₁-C₈ hydrocarbonoxy, orC₂-C₈ halohydrocarbonoxy wherein at least two carbon atoms separate thehalogen and oxygen atoms. Preferably, each Q¹ is alkyl or phenyl,especially C₁₋₄ alkyl, and each Q² is independently hydrogen or methyl.

Both homopolymer and copolymer poly(arylene ether)s are included. Thepreferred homopolymers are those comprising 2,6-dimethylphenylene etherunits. Suitable copolymers include random copolymers comprising, forexample, such units in combination with 2,3,6-trimethyl-1,4-phenyleneether units or copolymers derived from copolymerization of2,6-dimethylphenol with 2,3,6-trimethylphenol. Also included arepoly(arylene ether)s containing moieties prepared by grafting vinylmonomers or polymers such as polystyrenes, as well as coupledpoly(arylene ether) in which coupling agents such as low molecularweight polycarbonates, quinones, heterocycles and formals undergoreaction in known manner with the hydroxy groups of two poly(aryleneether) chains to produce a higher molecular weight polymer. Poly(aryleneether)s of the present invention further include combinations of any ofthe above.

The poly(arylene ether) generally has a number average molecular weightof about 3,000 to about 40,000 atomic mass units (AMU) and a weightaverage molecular weight of about 20,000 to about 80,000 AMU, asdetermined by gel permeation chromatography. The poly(arylene ether)generally may have an intrinsic viscosity of about 0.2 to about 0.6deciliters per grain (dL/g) as measured in chloroform at 25° C. Withinthis range, the intrinsic viscosity may preferably be up to about 0.5dL/g, more preferably up to about 0.47 dL/g. Also within this range, theintrinsic viscosity may preferably be at least about 0.3 dL/g. It isalso possible to utilize a high intrinsic viscosity poly(arylene ether)and a low intrinsic viscosity poly(arylene ether) in combination.Determining an exact ratio, when two intrinsic viscosities are used,will depend on the exact intrinsic viscosities of the poly(aryleneether)s used and the ultimate physical properties desired.

The poly(arylene ether)s are typically prepared by the oxidativecoupling of at least one monohydroxyaromatic compound such as2,6-xylenol or 2,3,6-trimethylphenol. Catalyst systems are generallyemployed for such coupling; they typically contain at least one heavymetal compound such as a copper, manganese or cobalt compound, usuallyin combination with various other materials.

Particularly useful poly(arylene ether)s for many purposes include thosethat comprise molecules having at least one aminoalkyl-containing endgroup. The aminoalkyl radical is typically located in an ortho positionrelative to the hydroxy group. Products containing such end groups maybe obtained by incorporating an appropriate primary or secondarymonoamine such as di-n-butylamine or dimethylamine as one of theconstituents of the oxidative coupling reaction mixture. Also frequentlypresent are 4-hydroxybiphenyl end groups, typically obtained fromreaction mixtures in which a by-product diphenoquinone is present,especially in a copper-halide-secondary or tertiary amine system. Asubstantial proportion of the polymer molecules, typically constitutingas much as about 90% by weight of the polymer, may contain at least oneof the aminoalkyl-containing and 4-hydroxybiphenyl end groups.

The first intimate blend may comprise poly(arylene ether) in an amountof about 10 to about 70 weight percent, based on the total weight of thecomposition. Within this range, it may be preferred to use at leastabout 18 weight percent of the poly(arylene ether). Also within thisrange, it may be preferred to use up to about 50 weight percent, morepreferably up to about 40 weight percent, of the poly(arylene ether).

The first intimate blend further comprises a poly(alkenyl aromatic)resin. The term “poly(alkenyl aromatic) resin” as used herein includespolymers prepared by methods known in the art including bulk,suspension, and emulsion polymerization, which contain at least 25% byweight of structural units derived from an alkenyl aromatic monomer ofthe formula

wherein R¹ is hydrogen, C₁-C₈ alkyl, halogen, or the like; Z is vinyl,halogen, C₁-C₈ alkyl, or the like; and p is 0 to 5. Preferred alkenylaromatic monomers include styrene, chlorostyrenes such asp-chlorostyrene, vinyltoluenes such as p-vinyltoluene, and the like. Thepoly(alkenyl aromatic) resins include homopolymers of an alkenylaromatic monomer; random copolymers of an alkenyl aromatic monomer, suchas styrene, with one or more different monomers such as acrylonitrile,butadiene, alpha-methylstyrene, ethylvinylbenzene, divinylbenzene andmaleic anhydride; and rubber-modified poly(alkenyl aromatic) resinscomprising blends and/or grafts of a rubber modifier and a homopolymerof an alkenyl aromatic monomer (as described above), wherein the rubbermodifier may be a polymerization product of at least one C₄-C₁₀nonaromatic diene monomer, such as butadiene or isoprene, and whereinthe rubber-modified poly(alkenyl aromatic) resin comprises about 98 toabout 70 weight percent of the homopolymer of an alkenyl aromaticmonomer and about 2 to about 30 weight percent of the rubber modifier.Within these ranges it may be preferred to use at least 88 weightpercent of the alkenyl aromatic monomer. It may also be preferred to useup to about 94 weight percent of the alkenyl aromatic monomer. It mayalso be preferred to use at least 6 weight percent of the rubbermodifier. It may also be preferred to use up to 12 weight percent of therubber modifier.

The stereoregularity of the poly(alkenyl aromatic) resin may be atacticor syndiotactic. Highly preferred poly(alkenyl aromatic) resins includeatactic and syndiotactic homopolystyrenes. Suitable atactichomopolystyrenes are commercially available as, for example, EB3300 fromChevron, and P1800 from BASF. Suitable syndiotactic homopolystyrenes arecommercially available, for example, under the tradename QUESTRA® (e.g.,QUESTRA® WA550) from Dow Chemical Company. Highly preferred poly(alkenylaromatic) resins further include the rubber-modified polystyrenes, alsoknown as high-impact polystyrenes or HIPS, comprising about 88 to about94 weight percent polystyrene and about 6 to about 12 weight percentpolybutadiene, with an effective gel content of about 10% to about 35%.These rubber-modified polystyrenes are commercially available as, forexample, GEH 1897 from General Electric Plastics, and BA 5350 fromChevron.

The first intimate blend may comprise the poly(alkenyl aromatic) resinin an amount of about 1 to about 46 weight percent, preferably about 3to about 46 weight percent, based on the total weight of thecomposition.

Alternatively, the amount of poly(alkenyl aromatic) resin may beexpressed as a fraction of the total of poly(arylene ether) andpoly(alkenyl aromatic) resin based on the combined weight ofpoly(arylene ether) and poly(alkenyl aromatic) resin. The first intimateblend may comprise preferably comprise poly(alkenyl aromatic) resin inan amount of about 10 to about 80 weight percent, based on the combinedweight of poly(arylene ether) and poly(alkenyl aromatic) resin. Withinthis range, it may be preferred to use at least about 20 weight percent,more preferably at least about 40 weight percent, of the poly(alkenylaromatic) resin based on the total of the poly(arylene ether) and thepoly(alkenyl aromatic) resin. Also within this range, it may bepreferred to use up to about 70 weight percent, more preferably up toabout 65 weight percent of the poly(alkenyl aromatic) resin based on thetotal of the poly(arylene ether) and the poly(alkenyl aromatic) resin.The proportions of poly(alkenyl aromatic) resin and poly(arylene ether)may be manipulated to control the glass transition temperature (T_(g))of the single phase comprising these two components relative to theT_(g) of the poly(arylene ether) alone, or relative to the meltingtemperature (T_(m)) of the polyolefin alone. For example, the relativeamounts of poly(alkenyl aromatic) resin and poly(arylene ether) may bechosen so that the poly(arylene ether) and the poly(alkenyl aromatic)resin form a single phase having a glass transition temperature at leastabout 20° C. greater, preferably at least about 30° C. greater, than theglass transition temperature of the poly(alkenyl aromatic) resin alone,which may be, for example, about 100° C. to about 110° C. Also, therelative amounts of poly(alkenyl aromatic) resin and poly(arylene ether)may be chosen so that the poly(arylene ether) and the poly(alkenylaromatic) resin form a single phase having a glass transitiontemperature up to about 15° C. greater, preferably up to about 10° C.greater, more preferably up to about 1° C. greater, than the T_(m) ofthe polyolefin alone. The relative amounts of poly(alkenyl aromatic)resin and poly(arylene ether) may be chosen so that the poly(aryleneether) and the poly(alkenyl aromatic) resin form a single phase having aglass transition temperature of about 130° C. to about 180° C.

The first intimate blend further comprises a hydrogenated blockcopolymer of an alkenyl aromatic compound and a conjugated diene. Thehydrogenated block copolymer is a copolymer comprising (A) at least oneblock derived from an alkenyl aromatic compound and (B) at least oneblock derived from a conjugated diene, in which the aliphaticunsaturated group content in the block (B) is reduced by hydrogenation.The arrangement of blocks (A) and (B) includes a linear structure and aso-called radial teleblock structure having branched chains.

Preferred of these structures are linear structures embracing diblock(A-B block), triblock (A-B-A block or B-A-B block), tetrablock (A-B-A-Bblock), and pentablock (A-B-A-B-A block or B-A-B-A-B block) structuresas well as linear structures containing 6 or more blocks in total of Aand B. More preferred are diblock, triblock, and tetrablock structures,with the A-B diblock and A-B-A triblock structures being particularlypreferred.

The alkenyl aromatic compound providing the block (A) is represented byformula:

wherein R² and R³ each independently represent a hydrogen atom, a C₁-C₈alkyl group, a C₂-C₈ alkenyl group, or the like; R⁴ and R⁸ eachindependently represent a hydrogen atom, a C₁-C₈ alkyl group, a chlorineatom, a bromine atom, or the like; and R⁵-R⁷ each independentlyrepresent a hydrogen atom, a C₁-C₈ alkyl group, a C₂-C₈ alkenyl group,or the like, or R⁴ and R⁵ are taken together with the central aromaticring to form a naphthyl group, or R⁵ and R⁶ are taken together with thecentral aromatic ring to form a naphthyl group.

Specific examples, of the alkenyl aromatic compounds include styrene,p-methylstyrene, alpha-methylstyrene, vinylxylenes, vinyltoluenes,vinylnaphthalenes, divinylbenzenes, bromostyrenes, chlorostyrenes, andthe like, and combinations comprising at least one of the foregoingalkenyl aromatic compounds. Of these, styrene, alpha-methylstyrene,p-methylstyrene, vinyltoluenes, and vinylxylenes are preferred, withstyrene being more preferred.

Specific examples of the conjugated diene include 1,3-butadiene,2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, andthe like. Preferred among them are 1,3-butadiene and2-methyl-1,3-butadiene, with 1,3-butadiene being more preferred.

In addition to the conjugated diene, the hydrogenated block copolymermay contain a small proportion of a lower olefinic hydrocarbon such as,for example, ethylene, propylene, 1-butene, dicyclopentadiene, anon-conjugated diene, or the like.

There is no particular restriction on the content of the repeating unitderived from the alkenyl aromatic compound in the hydrogenated blockcopolymer. Suitable alkenyl aromatic content may be about 10 to about 90weight percent based on the total weight of the hydrogenated blockcopolymer. Within this range, it may be preferred to have an alkenylaromatic content of at least about 40 weight percent, more preferably atleast about 50 weight percent, yet more preferably at least about 55weight percent. Also within this range, it may be preferred to have analkenyl aromatic content of up to about 85 weight percent, morepreferably up to about 75 weight percent.

There is no particular limitation on the mode of incorporation of theconjugated diene in the hydrogenated block copolymer backbone. Forexample, when the conjugated diene is 1,3-butadiene, it may beincorporated with about 1% to about 99% 1,2-incorporation with theremainder being 1,4-incorporation.

The hydrogenated block copolymer is preferably hydrogenated to such adegree that fewer than 50%, more preferably fewer than 20%, yet morepreferably fewer than 10%, of the unsaturated bonds in the aliphaticchain moiety derived from the conjugated diene remain unreduced. Thearomatic unsaturated bonds derived from the alkenyl aromatic compoundmay be hydrogenated to a degree of up to about 25%.

The hydrogenated block copolymer preferably has a number averagemolecular weight of about 5,000 to about 500,000 AMU, as determined bygel permeation chromatography (GPC) using polystyrene standards. Withinthis range, the number average molecular weight may preferably be atleast about 10,000 AMU, more preferably at least about 30,000 AMU, yetmore preferably at least about 45,000 AMU. Also within this range, thenumber average molecular weight may preferably be up to about 300,000AMU, more preferably up to about 200,000 AMU, yet more preferably up toabout 150,000 AMU.

The molecular weight distribution of the hydrogenated block copolymer asmeasured by GPC is not particularly limited. The copolymer may have anyratio of weight average molecular weight to number average molecularweight.

Some of these hydrogenated block copolymers have a hydrogenatedconjugated diene polymer chain to which crystallinity is ascribed.Crystallinity of the hydrogenated block copolymer can be determined bythe use of a differential scanning calorimeter (DSC), for example,DSC-II Model manufactured by Perkin-Elmer Co. Heat of fusion can bemeasured by a heating rate of, for example, 10° C./min in an inert gasatmosphere such as nitrogen. For example, a sample may be heated to atemperature above an estimated melting point, cooled by decreasing thetemperature at a rate of 10° C./min, allowed to stand for about 1minute, and then heated again at a rate of 10° C./min.

The hydrogenated block copolymer may have any degree of crystallinity.In view of a balance of mechanical strength of the resulting resincomposition, those hydrogenated block copolymers having a melting pointof about −40° C. to about 200° C. or having no definite melting point(i.e., having non-crystallinity), as measured according to theabove-described technique, are preferred. More preferably, thehydrogenated block copolymers have a melting point of at least about 0°C., yet more preferably at least about 20° C., still more preferably atleast about 50° C.

The hydrogenated block copolymer may have any glass transitiontemperature (T_(g)) ascribed to the hydrogenated conjugated dienepolymer chain. From the standpoint of low-temperature impact strength ofthe resulting resin composition, it preferably has a T_(g) of up toabout 0° C., more preferably up to about −120° C. The glass transitiontemperature of the copolymer can be measured by the aforesaid DSC methodor from the visco-elastic behavior toward temperature change as observedwith a mechanical spectrometer.

Particularly preferred hydrogenated block copolymers are thestyrene-(ethylene-butylene) diblock andstyrene-(ethylene-butylene)-styrene triblock copolymers obtained byhydrogenation of styrene-butadiene and styrene-butadiene-styrenetriblock copolymers, respectively.

Suitable hydrogenated block copolymers include those commerciallyavailable as, for example, KRATON® G1650, G1651, and G1652 availablefrom Kraton Polymers (formerly a division of Shell Chemical Company),and TUFTEC® H1041, H1043, H1052, H1062, H1141, and H1272 available fromAsahi Chemical. Preferred hydrogenated block copolymers include thehighly hydrogenated styrene(ethylene-butylene)-styrene triblockcopolymers commercially available as, for example, TUFTEC® H1043 fromAsahi Chemical.

The first intimate blend may comprise the hydrogenated block copolymerin an amount of about 1 to about 20 weight percent, preferably about 1to about 18 weight percent, more preferably about 1 to about 15 weightpercent, based on the total weight of the composition.

The first intimate blend further comprises an unhydrogenated blockcopolymer of alkenyl aromatic compound and a conjugated diene (referredto hereinafter as an “unhydrogenated block copolymer”). Theunhydrogenated block copolymer is a copolymer comprising (A) at leastone block derived from an alkenyl aromatic compound and (B) at least oneblock derived from a conjugated diene, in which the aliphaticunsaturated group content in the block (B) has not been reduced byhydrogenation. The alkenyl aromatic compound (A) and the conjugateddiene (B) are defined in detail above in the description of thehydrogenated block copolymer. The arrangement of blocks (A) and (B)includes a linear structure and a so-called radial teleblock structurehaving a branched chain.

Preferred of these structures are linear structures embracing diblock(A-B block), triblock (A-B-A block or B-A-B block), tetrablock (A-B-A-Bblock), and pentablock (A-B-A-B-A block or B-A-B-A-B block) structuresas well as linear structures containing 6 or more blocks in total of Aand B. More preferred are diblock, triblock, and tetrablock structures,with the A-B-A triblock structure being particularly preferred.

The unhydrogenated block copolymer may comprise about 10 to about 90weight percent of the (A) blocks. Within this range, it may be preferredto use at least about 20 weight percent (A) blocks. Also within thisrange, it may be preferred to use up to about 80 weight percent (A)blocks.

Particularly preferred unhydrogenated block copolymers includedstyrene-butadiene-styrene triblock copolymers.

Suitable unhydrogenated block copolymers may be prepared by knownmethods or obtained commercially as, for example, KRATON® D seriespolymers, including KRATON® D1101 and D1102, from Kraton Polymers(formerly a division of Shell Chemical).

The unhydrogenated block copolymer may be used at about 1 to about 20weight percent, preferably about 1 to about 15 weight percent, morepreferably about 1 to about 10 weight percent, based on the total weightof the composition.

The method comprises melt blending the first intimate blend and apolyolefin to form a second intimate blend. The polyolefin may be ahomopolymer or copolymer having at least about 80 weight percent ofunits derived from polymerization of ethylene, propylene, butylene, or amixture thereof. Examples of polyolefin homopolymers includepolyethylene, polypropylene, and polybutylene. Examples of polyolefincopolymers include random, graft, and block copolymers of ethylene,propylene, and butylene with each other, and further comprising up to 20weight percent of units derived from C₅-C₁₀ alpha olefins (excludingaromatic alphaolefins). Polyolefins further include blends of the abovehomopolymers and copolymers. Preferred polyolefins may have a flexuralmodulus of at least about 100,000 pounds per square inch (psi) at 23° C.as measured according to ASTM D790. Suitable polyolefins are maycomprise, for example, the linear low density polyethylene availablefrom ExxonMobil as LL-6201, the low density polyethylene available fromExxonMobil as LMA-027, the high density polyethylene available fromExxonMobil as HD-6605, the ultra-high molecular weight polyethyleneavailable as Type 1900 from Montell Polyolefins, and the polybutylene(polybutene-1) available as PB0110 from Montell Polyolefins.

Presently preferred polyolefins include propylene polymers. Thepropylene polymer may be a homopolymer of polypropylene. Alternatively,the propylene polymer may be a random, graft, or block copolymer ofpropylene and at least one olefin selected from ethylene and C₄-C₁₀alpha-olefins (excluding aromatic alpha-olefins), with the proviso thatthe copolymer comprises at least about 80 weight percent, preferably atleast about 90 weight percent, of repeating units derived frompropylene. Blends of such propylene polymers with a minor amount ofanother polymer such as polyethylene are also included within the scopeof propylene polymers. The propylene polymer may have a melt flow indexof about 0.1 to about 50 g/10 min, preferably about 1 to about 30 g/10min when measured according to ASTM D1238 at 2.16 kg and 200° C. Theabove-described propylene polymers can be produced by various knownprocesses. Commercially available propylene polymers may also beemployed.

Preferred propylene polymers include homopolypropylenes. Highlypreferred propylene polymers include homopolypropylenes having acrystalline content of at least about 20%, preferably at least about30%. Suitable isotactic polypropylenes are commercially available as,for example, PD403 pellets from Basell (formerly Montell Polyolefins ofNorth America).

The second intimate blend may comprise polyolefin in an amount of about10 to about 80 weight percent, preferably about 10 to about 70 weightpercent, more preferably about 10 to about 60 weight percent, based onthe total weight of the composition.

Although the method comprises melt blending the first intimate blendwith a polyolefin to form a second intimate blend, it is possible to adda portion of the polyolefin during formation of the first intimateblend. It is preferred that any polyolefin included in the firstintimate blend be less than the amount of polyolefin blended with thefirst intimate blend during formation of the second intimate blend. Itis preferred to add at least half of the total polyolefin duringformation of the second intimate blend.

The first intimate blend may, optionally, further comprise apolypropylene-polystyrene copolymer that is a graft copolymer, a diblockcopolymer, a multiblock copolymer, a radial block copolymer, or acombination comprising at least one of the foregoingpolypropylene-polystyrene copolymers. Alternatively, thepolypropylene-polystyrene copolymer may be added as a component of thesecond intimate blend. In a third alternative, about 1% to about 99% ofthe total polypropylene-polystyrene copolymer may be added as acomponent of the first intimate blend, with the remainder added as acomponent of the second intimate blend.

In a preferred embodiment, the polypropylene-polystyrene copolymer is agraft copolymer. The polypropylene-polystyrene graft copolymer is hereindefined as a graft copolymer having a propylene polymer backbone and oneor more styrene polymer grafts.

The propylene polymer material that forms the backbone or substrate ofthe polypropylene-polystyrene graft copolymer is (a) a homopolymer ofpropylene; (b) a random copolymer of propylene and an olefin selectedfrom the group consisting of ethylene and C₄-C₁₀ olefins, provided that,when the olefin is ethylene, the polymerized ethylene content is up toabout 10 weight percent, preferably up to about 4 weight percent, andwhen the olefin is a C₄-C₁₀ olefin, the polymerized content of theC₄-C₁₀ olefin is up to about 20 weight percent, preferably up to about16 weight percent; (c) a random terpolymer of propylene and at least twoolefins selected from the group consisting of ethylene and C₄-C₁₀alpha-olefins, provided that the polymerized C₄-C₁₀ alpha-olefin contentis up to about 20 weight percent, preferably up to about 16 weightpercent, and, when ethylene is one of the olefins, the polymerizedethylene content is up to about 5 weight percent, preferably up to about4 weight percent; or (d) a homopolymer or random copolymer of propylenewhich is impact-modified with an ethylene-propylene monomer rubber inthe reactor as well as by physical blending, the ethylene-propylenemonomer rubber content of the modified polymer being about 5 to about 30weight percent, and the ethylene content of the rubber being about 7 toabout 70 weight percent, and preferably about 10 to about 40 weightpercent. The C₄-C₁₀ olefins include the linear and branched C₄-C₁₀alpha-olefins such as, for example, 1-butene, 1-pentene,3-methyl-1-butene, 4-methyl-1-pentene, 1-hexene, 3,4-dimethyl-1-butene,1-heptene, 1-octene, 3-methyl-hexene, and the like. Propylenehomopolymers and impact-modified propylene homopolymers are preferredpropylene polymer materials. Although not preferred, propylenehomopolymers and random copolymers impact modified with anethylene-propylene-diene monomer rubber having a diene content of about2 to about 8 weight percent also can be used as the propylene polymermaterial. Suitable dienes include dicyclopentadiene, 1,6-hexadiene,ethylidene norbomene, and the like.

The term “styrene polymer”, used in reference to the grafted polymerpresent on the backbone of propylene polymer material in thepolypropylene-polystyrene graft copolymer, denotes (a) homopolymers ofstyrene or of an alkyl styrene having at least one C₁-C₄ linear orbranched alkyl ring substituent, especially a p-alkyl styrene; (b)copolymers of the (a) monomers with one another in all proportions; and(c) copolymers of at least one (a) monomer with alpha-methyl derivativesthereof, e.g., alpha-methylstyrene, wherein the alpha-methyl derivativeconstitutes about 1 to about 40% of the weight of the copolymer.

The polypropylene-polystyrene graft copolymer will typically compriseabout 10 to about 90 weight percent of the propylene polymer backboneand about 90 to about 10 weight percent of the styrene polymer graft.Within these ranges, the propylene polymer backbone may preferablyaccount for at least about 20 weight percent, of the total graftcopolymer; and the propylene polymer backbone may preferably account forup to about 40 weight percent of the total graft copolymer. Also withinthese ranges, the styrene polymer graft may preferably account for atleast about 50 weight percent, more preferably at least about 60 weightpercent, of the total graft copolymer.

The preparation of polypropylene-polystyrene graft copolymers isdescribed, for example, in U.S. Pat. No. 4,990,558 to DeNicola, Jr. etal. Suitable polypropylene-polystyrene graft copolymers are alsocommercially available as, for example, P1045H1 and P1085H1 from Basell.

When present, the polypropylene-polystyrene graft copolymer may be usedin an amount of about 0.5 to about 30 weight percent, preferably about0.5 to about 20 weight percent, more preferably about 0.5 to about 10weight percent, based on the total weight of the composition.

The method may, optionally, further comprise the addition of anethylene/alpha-olefin elastomeric copolymer. The alpha-olefin componentof the copolymer may be at least one C₃-C₁₀ alpha-olefin. Preferredalpha-olefins include propylene, 1-butene, and 1-octene. The elastomericcopolymer may be a random copolymer having about 25 to about 75 weightpercent, preferably about 40 to about 60 weight percent, ethylene andabout 75 to about 25 weight percent, preferably about 60 to about 40weight percent, alpha-olefin. Within these ranges, it may be preferredto use at least about 40 weight percent ethylene; and it may bepreferred to use up to about 60 weight percent ethylene. Also withinthese ranges, it may be preferred to use at least about 40 weightpercent alpha-olefin; and it may be preferred to use up to about 60weight percent alpha-olefin. The ethylene/alpha-olefin elastomericcopolymer may typically have a melt flow index of about 0.1 to about 20g/10 min at 2.16 kg and 200° C., and a density of about 0.8 to about 0.9g/ml.

Particularly preferred ethylene/alpha-olefin elastomeric copolymerrubbers include ethylene-propylene rubbers, ethylene-butene rubbers,ethylene-octene rubbers, and mixtures thereof.

The ethylene/alpha-olefin elastomeric copolymer may be preparedaccording to known methods or obtained commercially as, for example, theneat ethylene-propylene rubber sold as VISTALON® 878 by ExxonMobilChemical and the ethylene-butylene rubber sold as EXACT® 4033 byExxonMobil Chemical. Ethylene/alpha-olefin elastomeric copolymers mayalso be obtained commercially as blends in polypropylene as, forexample, the ethylene-propylene rubber pre-dispersed in polypropylenesold as product numbers Profax 7624 and Profax 8023 from Basell, and theethylene-butene rubber pre-dispersed in polypropylene sold as CatalloyK021P from Basell.

In a first embodiment, the ethylene/alpha-olefin elastomeric copolymermay be added during formation of the first intimate blend. In a secondembodiment, the ethylene/alpha-olefin elastomeric copolymer may be addedduring formation of the second intimate blend. In a third embodiment,about 1 to about 99% of the ethylene/alpha-olefin elastomeric copolymermay be added during formation of the first intimate blend, with theremainder added during formation of the second intimate blend. In afourth embodiment, the ethylene/alpha-olefin elastomeric copolymer maybe prepared as a heterophasic copolymer with the polyolefin, and theresulting heterophasic copolymer comprising ethylene/alpha-olefinelastomeric copolymer and polyolefin may be added during formation ofthe first intimate blend, or, preferably, during formation of the secondintimate blend.

When present, the ethylene/alpha-olefin elastomeric copolymer may beused in an amount of about 1 to about 20 weight percent, based on thetotal of the composition. Within this range, the ethylene/alpha-olefinelastomeric copolymer may preferably be used in an amount of at leastabout 3 weight percent. Also within this range, ethylene/alpha-olefinelastomeric copolymer may preferably be used in an amount up to about 15weight percent.

In one embodiment, the amount of ethylene/alpha-olefin elastomericcopolymer may be expressed as a fraction of the total of polyolefin andethylene/alpha-olefin elastomeric copolymer. Thus, when theethylene/alpha-olefin elastomeric copolymer is present, its amount maybe expressed as about 1 to about 60 weight percent, preferably about 10to about 40 weight percent, based on the combined weight of polyolefinand ethylene/alpha-olefin elastomeric copolymer.

The method may, optionally, comprise the addition of one or morereinforcing fillers. Reinforcing fillers may include, for example,inorganic and organic materials, such as fibers, woven fabrics andnon-woven fabrics of the E-, NE-, S-, T- and D-type glasses and quartz;carbon fibers, including poly(acrylonitrile) (PAN) fibers, vapor-growncarbon fibers, and especially graphitic vapor-grown carbon fibers havingaverage diameters of about 3 to about 500 nanometers (see, for example,U.S. Pat. Nos. 4,565,684 and 5,024,818 to Tibbetts et al., 4,572,813 toArakawa; 4,663,230 and 5,165,909 to Tennent, 4,816,289 to Komatsu etal., 4,876,078 to Arakawa et al., 5,589,152 to Tennent et al., and5,591,382 to Nahass et al.); potassium titanate single-crystal fibers,silicon carbide fibers, boron carbide fibers, gypsum fibers, aluminumoxide fibers, asbestos, iron fibers, nickel fibers, copper fibers,wollastonite fibers; and the like. The reinforcing fillers may be in theform of glass roving cloth, glass cloth, chopped glass, hollow glassfibers, glass mat, glass surfacing mat, and non-woven glass fabric,ceramic fiber fabrics, and metallic fiber fabrics. In addition,synthetic organic reinforcing fillers may also be used including organicpolymers capable of forming fibers. Illustrative examples of suchreinforcing organic fibers are poly(ether ketone), polyimidebenzoxazole, poly(phenylene sulfide), polyesters, aromatic polyamides,aromatic polyimides or polyetherimides, acrylic resins, and poly(vinylalcohol). Fluoropolymers such as polytetrafluoroethylene, may be used.Also included are natural organic fibers known to one skilled in theart, including cotton cloth, hemp cloth, and felt, carbon fiber fabrics,and natural cellulosic fabrics such as Kraft paper, cotton paper, andglass fiber containing paper. Such reinforcing fillers could be in theform of monofilament or multifilament fibers and could be used eitheralone or in combination with another type of fiber, through, forexample, coweaving or core-sheath, side-by-side, orange-type or matrixand fibril constructions or by other methods known to one skilled in theart of fiber manufacture. They may be in the form of, for example, wovenfibrous reinforcements, non-woven fibrous reinforcements, or papers.

Preferred reinforcing fillers include glass fibers. Preferred glassfibers may have diameters of about 2 to about 25 micrometers, morepreferably about 10 to about 20 micrometers, yet more preferably about13 to about 18 micrometers. The length of the glass fibers may be about0.1 to about 20 millimeters, more preferably about 1 to about 10millimeters, yet more preferably about 2 to about 8 millimeters. Glassfibers comprising a sizing to increase their compatibility with thepolyolefin are particularly preferred. Suitable sizings are described,for example, in U.S. Pat. No. 5,998,029 to Adzima et al. Suitable glassfibers are commercially available as, for example, product numbers147A-14P (14 micrometer diameter) and 147A-17P (17 micrometer diameter)from Owens Corning.

Preferred reinforcing fillers further include talc. There are noparticular limitations on the physical characteristics of the talc.Preferred talcs may have an average particle size of about 0.5 to about25 micrometers. Within this range, it may be preferred to use a talchaving an average particle size up to about 10 micrometers, morepreferably up to about 5 micrometers. For some uses of the composition,it may be preferred to employ a talc that is F.D.A. compliant (i.e.,compliant with U.S. Food and Drug Administration regulations). Suitabletalcs include, for example, the F.D.A. compliant talc having an averageparticle size of about 3.2 micrometers sold as CIMPACT® 610(C) fromLuzenac.

The compatibility of the reinforcing filler and the polyolefin may beimproved not just with sizings on the surface of the reinforcingfillers, but also by adding to the composition a graft copolymercomprising a polyolefin backbone and polar grafts formed from one ormore cyclic anhydrides. Such materials include graft copolymers ofpolyolefins and C₄-C₁₂ cyclic anhydrides, such as, for example, thoseavailable from ExxonMobil under the tradename EXXELOR® and from DuPontunder the tradename FUSABOND®M. Examples of suitablepolyolefin-graft-cyclic anhydride copolymers are thepolypropylene-graft-maleic anhydride materials supplied by ExxonMobil asEXXELOR® PO1020 and by DuPont as FUSABOND® M613-05. Suitable amounts ofsuch materials may be readily determined and are generally about 0.1 toabout 10 weight percent, based on the total weight of the composition.Within this range, a polyolefin-graft-cyclic anhydride copolymer amountof at least about 0.5 weight percent may be preferred. Also within thisrange, a polyolefin-graft-cyclic anhydride copolymer amount of up toabout 5 weight percent may be preferred.

The one or more reinforcing fillers may be melt blended with the firstintimate blend and the polyolefin during formation of the secondintimate blend. Alternatively, the method may comprise an additionalblending step in which the one or more reinforcing fillers are blendedwith the second intimate blend. In another alternative, it may beadvantageous to add the reinforcing fillers, especially particulatefillers (i.e., those having an aspect ratio less than about 3), duringformation of the first intimate blend.

The method may, optionally, comprise the addition of additives to thecomposition. Such additives may include, for example, stabilizers, moldrelease agents, processing aids, flame retardants, drip retardants,nucleating agents, UV blockers, dyes, pigments, particulate fillers(i.e., fillers having an aspect ratio less than about 3), antioxidants,anti-static agents, blowing agents, and the like. Such additives arewell known in the art and appropriate amounts may be readily determined.There is no particular limitation on how or when the additives areadded. For example, the additives may be added during formation of thefirst intimate blend. Alternatively, the additives may be added duringformation of the second intimate blend. In another alternative, theadditives may be added in a separate step following formation of thesecond intimate blend.

As the composition is defined as comprising multiple components, it willbe understood that each component is chemically distinct, particularlyin the instance that a single chemical compound may satisfy thedefinition of more than one component.

In a preferred embodiment, the method of preparing a thermoplasticcomposition, comprises: melt-blending to form an first intimate blendcomprising about 10 to about 59 weight percent of a poly(arylene ether),about 1 to about 46 weight percent of a poly(alkenyl aromatic) resin,about 1 to about 20 weight percent of a hydrogenated block copolymer ofalkenyl aromatic compound and a conjugated diene, and about 1 to about20 weight percent of an unhydrogenated block copolymer of an alkenylaromatic compound and a conjugated diene; and melt-blending to form asecond intimate blend comprising the first intimate blend, and about 10to about 60 weight percent of a polyolefin; wherein all weight percentsare based on the total weight of the composition.

In another preferred embodiment, the method of preparing a thermoplasticcomposition, comprises: melt-blending to form an first intimate blendcomprising about 10 to about 59 weight percent of a poly(arylene ether),about 1 to about 46 weight percent of a poly(alkenyl aromatic) resin,about 1 to about 20 weight percent of a hydrogenated block copolymer ofalkenyl aromatic compound and a conjugated diene, and about 1 to about20 weight percent of an unhydrogenated block copolymer of an alkenylaromatic compound and a conjugated diene; and melt-blending to form asecond intimate blend comprising the first intimate blend, about 10 toabout 60 weight percent of a polyolefin, and about 1 to about 20 weightpercent of an ethylene/alpha-olefin elastomeric copolymer; wherein allweight percents are based on the total weight of the composition.

In yet another preferred embodiment, the method of preparing athermoplastic composition, comprises: melt-blending to form an firstintimate blend comprising about 10 to about 59 weight percent of apoly(arylene ether), about 1 to about 46 weight percent of apoly(alkenyl aromatic) resin, about 1 to about 20 weight percent of ahydrogenated block copolymer of alkenyl aromatic compound and aconjugated diene, about 1 to about 20 weight percent of anunhydrogenated block copolymer of an alkenyl aromatic compound and aconjugated diene, and about 0.5 to about 30 weight percent of apolypropylene-polystyrene graft copolymer; and melt-blending to form asecond intimate blend comprising the first intimate blend and about 10to about 60 weight percent of a polyolefin; wherein all weight percentsare based on the total weight of the composition.

In another preferred embodiment, the method of preparing a thermoplasticcomposition comprises: melt-blending to form an first intimate blendcomprising about 10 to about 59 weight percent of a poly(arylene ether),about 1 to about 46 weight percent of a poly(alkenyl aromatic) resin,about 1 to about 20 weight percent of a hydrogenated block copolymer ofalkenyl aromatic compound and a conjugated diene, and about 1 to about20 weight percent of an unhydrogenated block copolymer of an alkenylaromatic compound and a conjugated diene; and melt-blending to form asecond intimate blend comprising the first intimate blend, about 10 toabout 60 weight percent of a polyolefin, and about 1 to about 50 weightpercent of a reinforcing filler; wherein all weight percents are basedon the total weight of the composition.

In another preferred embodiment, the method of preparing a thermoplasticcomposition comprises: melt-blending to form an first intimate blendcomprising about 10 to about 59 weight percent of a poly(arylene ether),about 1 to about 46 weight percent of a poly(alkenyl aromatic) resin,about 1 to about 20 weight percent of a hydrogenated block copolymer ofalkenyl aromatic compound and a conjugated diene, and about 1 to about20 weight percent of an unhydrogenated block copolymer of an alkenylaromatic compound and a conjugated diene; and melt-blending to form asecond intimate blend comprising the first intimate blend and about 10to about 60 weight percent of a polyolefin; and melt-blending to form athird intimate blend comprising the second intimate blend; and about 1to about 50 weight percent of a reinforcing filler; wherein all weightpercents are based on the total weight of the composition.

Another embodiment is a method of preparing a thermoplastic composition,comprising: melt-blending a poly(arylene ether), a poly(alkenylaromatic) resin, a hydrogenated block copolymer of an alkenyl aromaticcompound and a conjugated diene, and an unhydrogenated block copolymerof an alkenyl aromatic compound and a conjugated diene to form a firstintimate blend; and melt-blending a polyolefin, additional hydrogenatedblock copolymer, and, optionally, an ethylene/alpha-olefin elastomericcopolymer, with the first intimate blend to form a second intimate blendcomprising the first intimate blend, the polyolefin, and the additionalhydrogenated block copolymer. In this embodiment, the additionalhydrogenated block copolymer added to form the second intimate blend maybe the same or different form the hydrogenated block copolymer used toform the first intimate blend. For example, astyrene-(ethylene-butylene)-styrene block copolymer may be added as thehydrogenated block copolymer to form the form the first intimate blend,and more of the same styrene-(ethylene-butylene)-styrene block copolymermay be added as the additional hydrogenated block copolymer to form thesecond intimate blend. As another example, astyrene-(ethylene-butylene)-styrene block copolymer may be added as thehydrogenated block copolymer to form the form the first intimate blend,and a styrene-(ethylene-propylene)-styrene block copolymer may be addedas the additional hydrogenated block copolymer to form the secondintimate blend. In a preferred embodiment, the additional hydrogenatedblock copolymer used to form the second intimate blend is astyrene-(ethylene-butylene)-styrene triblock copolymer having a styrenecontent of about 50 to about 90 weight percent. The amount of theadditional hydrogenated block copolymer is about 1 to about 20 weightpercent, based on the total weight of the composition. Within thisrange, the additional hydrogenated block copolymer amount is preferablyat least about 1.5 weight percent, more preferably at least 2 weightpercent. Also within this range, the additional hydrogenated blockcopolymer amount is preferably up to about 15 weight percent, morepreferably up to about 5 weight percent.

Another embodiment is a method of preparing a thermoplastic composition,comprising: melt-blending to form a first intimate blend comprisingabout 10 to about 59 weight percent of a poly(arylene ether), about 1 toabout 46 weight percent of a poly(alkenyl aromatic) resin, about 1 toabout 20 weight percent of a hydrogenated block copolymer of alkenylaromatic compound and a conjugated diene, and about 1 to about 20 weightpercent of an unhydrogenated block copolymer of an alkenyl aromaticcompound and a conjugated diene; and melt-blending about 10 to about 60weight percent of a polyolefin and about 1 to about 20 weight percent ofadditional hydrogenated block copolymer with the first intimate blend toform a second intimate blend comprising the first intimate blend, about10 to about 60 weight percent of the polyolefin, and about 1 to about 20weight percent of additional hydrogenated block copolymer; wherein allweight percents are based on the total weight of the composition.

Another embodiment is a method of preparing a thermoplastic composition,comprising: melt-blending to form a first intimate blend comprisingabout 10 to about 59 weight percent of a poly(arylene ether) comprising2,6-dimethyl-1,4-phenylene ether units, 2,3,6-trimethyl-1,4-phenyleneether units, or a combination thereof; about 1 to about 46 weightpercent of polystyrene or rubber-modified polystyrene; about 1 to about20 weight percent of a styrene-(ethylene-butylene)-styrene blockcopolymer having a styrene content of about 50 to about 90 weightpercent; and about 1 to about 20 weight percent of astyrene-butadiene-styrene block copolymer; and melt-blending about 10 toabout 60 weight percent of polypropylene and about 1 to about 20 weightpercent of additional styrene-(ethylene-butylene)-styrene blockcopolymer having a styrene content of about 50 to about 90 weightpercent with the first intimate blend to form a second intimate blendcomprising the first intimate blend, about 10 to about 60 weight percentof the polypropylene, and about 1 to about 20 weight percent ofadditional styrene-(ethylene-butylene)-styrene block copolymer having astyrene content of about 50 to about 90 weight percent; wherein allweight percents are based on the total weight of the composition.

Another embodiment is a thermoplastic composition prepared according toany of the above-described methods.

While the method has been described in terms of poly(aryleneether)-polyolefin blends, it is generally applicable to a wide varietyof thermoplastic blends in which a stiffer (e.g., higher flexuralmodulus) polymer is to be dispersed in the matrix of a less stiff (e.g.,lower flexural modulus) polymer to produce blends having consistentlyreproducible properties. Furthermore, while the method has beendescribed in terms of upstream and downstream addition of componentsduring a single extruder pass, the first and second intimate blends maybe formed in separate passes. For example, the a poly(arylene ether),poly(alkenyl aromatic) resin, hydrogenated block copolymer, andunhydrogenated block copolymer may be added to an extruder to form afirst intimate blend which is extruded into strands and pelletized. Thispelletized first intimate blend may then be added to an extruder in asecond pass, with downstream addition of the polyolefin, additionalhydrogenated block copolymer, and optional rubber and/or filler and/oradditives, to form the second intimate blend.

The method is particularly useful for thermoplastic blends comprising atleast three components, where the first component is intended to formthe matrix phase of the final blend, the second component is intended tobe a dispersed phase, and the third component is intended to reside atleast partially at the interface of the matrix phase and the dispersedphase. Thus, the method may comprise: melt-blending to form a firstintimate blend comprising a dispersed phase component and an interfacialcomponent; and melt-blending to form a second intimate blend comprisingthe first intimate blend and a matrix component.

The invention is further illustrated by the following non-limitingexamples.

EXAMPLES 1-3 Comparative Examples 1, 2

A single formulation was compounded by various methods in a twin screwextruder. The components and amounts of the formulation are summarizedin Table 1.

TABLE 1 material weight abbreviation description percent PPpolypropylene, obtained as PH280 from Montell 57.2 Polyolefin Inc. EPRethylene propylene rubber, obtained as VISTALON ® 878 7.3 fromExxonMobil Chemical PP-g-PS polypropylene-polystyrene graft copolymer,obtained as 13.3 Interloy PH 1045H1 from Montell Polyolefin Inc. SEBSG1652 styrene-(ethylene-butadiene)-styrene copolymer, obtained 2.7 asKRATON ® G1652 from Kraton Polymers PPE poly(2,6-dimethylphenyleneether), IV = 0.40 dl/g, obtained 6.7 from General Electric Company SBSstyrene-butadiene-styrene block copolymer, obtained as 5.1 KRATON ®D1101 from Kraton Polymers xPS homopolystyrene, also known as crystalpolystyrene, 7.7 obtained as PP-738 from Huntsman Chemical, MFI = 10.5g/10 min at 200 C., 5 kg

General Blending/Compounding Procedure: Using quantities specified inTable 1, PP-g-PS, PPE, xPS, HIPS, SEBS and SBS were hand mixed in a bag.The resulting mixture was subsequently mixed aggressively with amechanical blender for uniformity. The uniform mixture was subsequentlyfed through a feeder and entered into an extruder at the extruderinitial entry point. When the quantity of the poly(alkenyl aromatic)resin is equal to or greater than 10% of the total blend weight, thepoly(alkenyl aromatic) resin may be fed thorough a separate upstreamfeeder. Components PP and EPR, in quantities specified in Table 1, werefed either upstream or downstream. Downstream addition corresponded toaddition at barrel 6 of a 10-barrel extruder.

General Extrusion: a 30 millimeter co-rotating twin-screw extruder wasused. Blends were melt extruded at 520° F., 450-500 rpm, and athroughput rate of 30-50 pounds per hour. Melt from the extruder wasforced through a three-hole die to produce melt strands. These strandswere rapidly cooled by passing them through a cold-water bath. Thecooled strands were chopped into pellets. Pellets were dried in an ovenat 200° F. for 2-4 hours.

General Molding: ASTM parts were molded on a 120 tonne molding machine(manufacturer Van Dorn) at 450-550° F. barrel temperature and 100-120°F. mold temperature.

Parts were tested according to ASTM methods. Izod notched impact wasmeasured at 23° C. and −30° C. according to ASTM D256. Dynatup (fallingdart) total energy and energy to failure were measured at 23° C. and−30° C. and at 5 and 7.5 mph according to ASTM D3763. Heat distortiontemperature (HDT) was measured at 66 psi and 264 psi on ⅛ inch samplesaccording to ASTM D648. Flexural modulus and flexural strength weremeasured at 23° C. on ⅛ inch samples according to ASTM D790. Tensilestrength and tensile elongation at break were measured at 23° C.according to ASTM D638. Where presented, standard deviations reflectmeasurements on five samples.

Process variations included the extruder's barrel temperature, the screwrotation rate (“RPM”), the throughput rate, the fraction of polyolefinadded upstream (i.e., during formation of the first intimate blend)versus downstream (i.e., during formation of the second intimate blend),and the fraction of SEBS and PP-g-PS added upstream versus downstream.For all formulations, formation of the first intimate blend utilizedhigh intensity mixing abbreviated as “+1” and corresponding to the useof 6 mixing elements on each screw shaft, and formation of the secondintimate blend utilized low intensity mixing abbreviated as “−1” andcorresponding to the use of 5 mixing elements on each screw shaft. Also,for all for examples and comparative examples, PPE, xPS, and SBS, wereadded upstream, and EPR was added downstream. Examples differed fromComparative Examples in that Examples utilized downstream addition ofall PP, whereas Comparative Examples utilized addition of 75% PPupstream and 25% PP downstream. Process variations and resultingproperties are summarized in Table 2. Standard deviations reflectmeasurements on five samples. The best overall property balance wasexhibited by Example 1, which utilized downstream addition of PP, andupstream addition of PP-g-PS and SEBS.

TABLE 2 Comp. Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 1 Ex. 2 PROCESS VARIATIONSupstream mixing +1 +1 +1 +1 +1 downstream mixing +1 +1 +1 +1 +1 RPM 450450 450 250 250 Throughput Rate (lb/h) 55 25 55 55 25 Barrel Temp (° C.)240 240 290 290 240 fraction PP added Upstream (%) 0 0 0 75 75 fraction(PP-g-PS + SEBS) 100 0 0 0 0 added upstream (%) PROPERTIES Notched Izod,23° C. (ft-lb/in) 7.219 2.742 2.961 3.309 4.400 std dev (ft-lb/in) 0.3910.091 0.195 0.103 0.186 rel std dev (%) 5.4 3.3 6.6 3.1 4.2 NotchedIzod, −30° C. (ft-lb/in) 1.385 0.723 0.851 1.183 1.257 dev (ft-lb/in)0.053 0.071 0.144 0.172 0.109 rel std dev (%) 3.8 9.8 16.9 14.5 8.7Dynatup Total Energy, 5 mph, 26.23 16.98 22.03 24.77 22.27 23° C.(ft-lb) std dev (ft-lb) 0.34 5.06 3.12 1.54 4.55 rel std dev (%) 1.329.8 14.2 6.2 20.4 Dynatup Total Energy, 5 mph, 13.51 0.9 3.66 12.113.19 −30° C. (ft-lb) std dev (ft-lb) 2.09 0.47 2.38 1.53 0.81 rel stddev (%) 15.5 52.2 65.0 12.6 25.4 Flexural Modulus, 23° C., ⅛ in 186,300202,700 200,600 207,400 199,100 (psi) std dev (ft-lb) 4848 2743 28232834 4825 rel std dev (%) 2.6 1.4 1.4 1.4 2.4

EXAMPLES 4-10

Using the same formulation as above, samples were compounded withprocess variations including the intensities of upstream and downstreammixing, the extruder barrel temperature, the screw rotation rate(“RPM”), and the throughput rate. For all samples, PPE, xPS, SBS, SEBS,and PP-g-PS were added upstream, and PP and EPR were added downstream.Results are presented in Table 3.

TABLE 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 PROCESS VARIATIONSupstream mixing −1 −1 −1 +1 +1 +1 +1 downstream mixing −1 +1 +1 −1 +1 +1+1 RPM 450 350 350 450 450 450 450 Throughput Rate (kg/h) 40 55 55 55 5525 25 Barrel Temperature (° C.) 290 240 240 240 290 290 240 PROPERTIESHDT, 66 psi, ⅛ in (° F.) 221.7 211.1 207.9 206.4 219.8 216.0 215.8 HDT,264 psi, ⅛ in (° F.) 143.6 144.0 141.1 139.1 144.1 141.5 142.3 NotchedIzod, 23° C. (ft-lb/in) 2.373 3.804 4.444 7.219 2.273 1.567 2.667 stddev (fl-lb/in) 0.104 0.200 0.079 0.391 0.077 0.081 0.101 rel std dev (%)4.4 5.3 1.8 5.4 3.4 5.2 3.8 Notched Izod, −30° C. (ft-lb/in) 0.896 1.2731.037 1.385 0.827 0.638 0.933 std dev (ft-lb/in) 0.088 0.077 0.026 0.0530.194 0.030 0.055 rel std dev (%) 9.8 6.0 2.5 3.8 23.5 4.7 5.9 DynatupTotal Energy, 23° C., 7.5 mph (ft-lb) 10.34 15.10 16.66 27.84 19.7913.65 24.88 std dev (ft-lb) 2.63 1.07 1.13 0.39 6.16 4.81 0.98 rel stddev (%) 25.4 7.1 6.8 1.4 31.1 35.2 3.9 Dynatup Total Energy, 23° C.,12.32 14.22 16.93 26.23 14.57 8.56 18.67 5 mph (ft-lb) std dev (ft-lb)5.59 2.54 0.62 0.34 6.26 3.62 5.14 rel std dev (%) 45.4 17.9 3.7 1.343.0 42.3 27.5 Dynatup Total Energy, 1.38 1.67 1.09 13.51 2.28 1.31 6.27−30° C., 5 mph (ft-lb) std dev (ft-lb) 0.67 0.40 0.23 2.09 2.01 0.361.98 rel std dev (%) 48.6 24.0 21.1 15.5 88.2 27.5 31.6 FlexuralModulus, 23° C., 202,400 192,400 185,700 186,300 198,800 193,500 198,200⅛ in (psi) std dev (psi) 5235 2846 4341 4848 853 1767 1085 rel std dev(%) 2.6 1.5 2.3 2.6 0.4 0.9 0.5 Tensile Elongation at break, 56.2 69.061.1 100.6 66.5 61.9 55.8 23° C. (%)

EXAMPLE 11

A composition was compounded using the formulation detailed in Table 4.SEBS H1043 is a hydrogenated styrene-butadiene-styrene triblockcopolymer having 66 weight percent polystyrene and obtained in pelletform as TUFTEC® H1043 from Asahi Chemical. All component amounts areexpressed in parts by weight. Upstream mixing employed six mixingelements on each screw shaft; downstream mixing employed three mixingelements on each screw shaft. Except for EPR and 75% of the PP, whichwere added downstream, all components were added upstream to theextruder. The extruder barrel temperature was 288° F., and the screwrotation rate was 450 RPM. Properties were measured as discussed above,and results are given in Table 4.

TABLE 4 Ex. 11 COMPOSITION PP 33.90 EPR 6.20 PP-g-PS 5.90 SBS 11.40 SEBSH1043 6.30 xPS 20.20 PPE 16.20 PROPERTIES Flex Modulus, 23° C., ⅛″ (psi)221,000 Flex Strength at Yield (psi) 7300 HDT, 66 psi, ⅛″ (° F.) 229HDT, 264 psi, ⅛″ (° F.) 170 Notched Izod, 23° C. (ft-lb/in) 8.9 NotchedIzod, −30° C. (ft-lb/in) 2.5 Unnotched Izod, 23° C. (ft-lb/in) — Energyto Fail, 23° C., 7.5 mph (ft-lb) 19.2 Total Energy, 23° C., 7.5 mph(ft-lb) 32.4 Energy to Fail, −30° C., 7.5 mph (ft-lb) 14.7 Total Energy,−30° C., 7.5 mph (ft-lb) 17 Energy to Fail, −30° C., 5 mph (ft-lb) —Total Energy, −30° C., 5 mph (ft-lb) — Tensile strength at yield (psi)5,060 Tensile Stress at break (psi) 5,079 Tensile Elongation at break(%) 273

EXAMPLES 12-47

These examples collectively illustrate the effect of mixing energy inputon properties of a single composition.

The composition is summarized in Table 5; all amounts are in units ofweight percent, based on the total composition. Components were asspecified in Table 1, except that EPR was obtained as PROFAX 7624 fromMontell Polyolefins, which is a heterophasic/pre-dispersed blend ofabout 20 weight percent EPR in polypropylene; polypropylene (PP) was acombination of PD403 obtained from Montell Polyolefin and the 80 weightpercent polypropylene content of PROFAX 7624.

TABLE 5 PPE 16.14 SBS 11.36 xPS 20.13 SEBS H1043 6.28 PP-g-PS 5.88 PP33.76 EPR 6.20 thermal stabilizers 0.25

Compositions were extruded using upstream additions of all componentsexcept for EPR and PP, which were added downstream. The barreltemperature was 500° F. for all samples. Mixing energy input was variedby changing the number of downstream mixing elements in the extruder andby changing the extruder screw speed and the total feed rate of allcomponents. The energy input for each example was calculated accordingto the formulaE=V*A/Twhere E is the energy input (in kW-hr/kg), V is the voltage applied tothe DC extruder motor (in volts), A is the current drawn by the extrudermotor (in amps), and T is the material throughput (in grams).

ASTM parts were molded as described above, and values of Energy toFailure at −30° C., 5 mph, were measured according to ASTM D3763. Theresults, presented in Table 6, indicate a significant correlationbetween higher downstream energy input and higher values of Energy toFailure.

TABLE 6 Energy Input Energy to Failure at Ex. No. (kW-hr/kg) −30° C., 5mph (ft-lb) 12 0.228 11.83 13 0.241 15.23 14 0.218 11.61 15 0.234 11.3216 0.229 5.87 17 0.224 10.32 18 0.211 8.99 19 0.227 10.52 20 0.215 12.4121 0.247 19.36 22 0.233 6.74 23 0.216 10.72 24 0.227 13.46 25 0.25114.80 26 0.224 11.03 27 0.226 10.10 28 0.225 5.80 29 0.243 18.11 300.246 13.30 31 0.230 11.10 32 0.241 16.94 33 0.223 6.74 34 0.233 9.54 350.222 3.79 36 0.224 7.74 37 0.267 21.74 38 0.255 21.16 39 0.245 20.29 400.240 20.06 41 0.267 14.88 42 0.245 13.29 43 0.245 23.24 44 0.245 21.7145 0.245 21.41 46 0.245 23.47 47 0.245 22.28

EXAMPLES 48-59

These examples further illustrate the effects on properties ofdownstream versus upstream addition of polyolefin, intensity of upstreamkneading, and intensity of downstream kneading.

The composition is detailed in Table 5, above. Process variables weredownstream vs. upstream addition of PP and EPR, high (+1) vs. low (−1)intensity upstream kneading, and high (+1) vs. low (−1) intensitydownstream kneading. High intensity upstream and downstream kneadingcorresponded to use of assemblies of multiple right-handed, left-handed,and neutral kneading elements as depicted in FIG. 1 as Kneading 1 (+1)and Kneading 2 (+1), respectively. Likewise, low intensity upstream anddownstream kneading corresponded to the use of assemblies depicted inFIG. 1 as Kneading 1 (−1) and Kneading 2 (−1), respectively. In thescrew elements labeled in FIG. 1, RSE stands for right-handed screwelement, SFE stands for single flighted element, RKB stands forright-handed kneading block, NKB stands for neutral kneading block, andLKB stands for left-handed kneading block. Each labeled element includesa two-number or three-number designation following the three letteracronyms described above. For conveying elements (i.e., those elementsfor which the third letter of the three letter acronym is “E”), thefirst number is the pitch (i.e., the axial length in millimetersrequired for a flight to make a full revolution). For kneading blocks(i.e., those elements for which the third letter of the three letteracronym is “B”), the first number is the offset angle of each individualdisk to its neighbor, and the second number is the total number of disksthat make up the screw element. For all screw elements, the last numberis the total length of the screw element in millimeters. The numberedsections above the screw elements are known as barrel numbers. Eachkneading section is bounded by the first and last kneading blocks withinthat section. For example, “Kneading 1+1” is bounded on the left by RKB45/5/28 and on the right by LKB 45/5/14. It will be understood that thelower half of the figure is meant to show the “opposite” versions ofKneading 1 and Kneading 2 that may be inserted into the correspondingkneading sections in the upper half of the figure.

Process variations and property values are presented in Table 7. Acomparison of Examples 52 and 53 versus 54 and 55 illustrates the effectof upstream versus downstream addition of polyolefin, respectively, forhigh intensity upstream mixing and low intensity downstream mixing. Notethat Examples 54 and 55, with downstream addition of polyolefin, exhibitsuperior Notched Izod impact strength at 23° C., Energy to Failure at−30° C., Total Energy at −30° C., Flexural Strength at Yield, andTensile Strength at Yield compared to Examples 52 and 53 with upstreamaddition of polyolefin.

A comparison of Examples 54 and 55 versus 56 and 57 illustrates theeffect of low versus high intensity downstream kneading, respectively,for downstream addition of PP and EPR and high intensity upstreammixing. Note that Examples 54 and 55, with low intensity downstreamkneading, exhibit superior Notched Izod impact strength at 23° C. and−30° C. compared to Examples 56 and 57 with high intensity downstreamkneading.

TABLE 7 Ex. 48 Ex. 49 Ex. 50 Ex. 51 Ex. 52 Ex. 53 PROCESS VARIATIONS %(PP + EPR) added 0 0 100 100 0 0 downstream upstream mixing −1 −1 −1 −1+1 +1 downstream mixing −1 −1 −1 −1 −1 −1 PROPERTIES HDT, 66 psi, ⅛ in(° F.) 223.7 225.1 227.9 228.3 — 230.4 std dev (° F.) 9.1 5.7 0.6 2.3 —1.9 HDT, 264 psi, ⅛ in (° F.) 163.2 166.6 164.4 164.6 165.6 166.7 stddev (° F.) 0.9 2.4 0.6 2.4 1.3 1.4 Notched Izod, 23° C. (ft-lb/in) 8.18.2 7.8 8.8 7.8 7.6 std dev (ft-lb/in) 0.1 0.3 0.3 0.4 0.3 0.2 NotchedIzod, −30° C. (ft-lb/in) 2.3 2.9 2.6 2.6 2.4 3.0 std dev (ft-lb/in) 0.40.8 0.5 0.3 0.3 0.7 Dynatup Energy to Failure, 23° C., 7.5 mph (ft-lb)17.55 17.61 17.61 17.74 17.90 17.98 std dev (ft-lb) 0.46 0.24 0.59 0.540.23 0.51 Dynatup Total Energy, 23° C., 28.57 26.69 25.38 27.02 29.1630.39 7.5 mph (ft-lb) std dev (ft-lb) 1.78 2.97 3.19 2.64 2.44 1.03Dynatup Energy to Failure, 11.13 7.83 6.41 8.22 10.03 10.73 −30° C., 7.5mph (ft-lb) std dev (ft-lb) 4.17 3.42 2.30 4.42 5.26 5.40 Dynatup TotalEnergy, 12.51 8.32 7.08 8.64 10.52 11.22 −30° C., 7.5 mph (ft-lb) stddev (ft-lb) 5.67 3.43 2.68 4.54 5.42 5.55 Dynatup Energy to Failure,15.04 15.11 9.82 10.14 17.87 17.93 −30° C., 5 mph (ft-lb) std dev(ft-lb) 4.11 5.46 3.97 4.63 3.08 4.35 Dynatup Total Energy, 15.50 15.5410.16 10.49 19.06 19.69 −30° C., 5 mph (ft-lb) std dev (ft-lb) 4.23 5.584.04 4.74 4.13 6.52 Flexural Modulus, 23° C., ⅛ in 203,900 210,300209,800 214,000 213,100 212,200 (psi) std dev (psi) 980 755 3936 26123368 1532 Flexural Strength at Yield, 6,704 6,830 6,878 6,994 6,8886,875 23° C., ⅛ in (psi) std dev (psi) 21 17 32 32 22 23 TensileStrength at Yield, 4,693 4,721 4,809 4,818 4,703 4,693 23° C., ⅛ in(psi) std dev (psi) 27.4 5.8 19.4 10.8 6.0 27.3 Tensile Strength atBreak, 4,216 4,454 4,358 4,508 4,588 4,216 23° C., ⅛ in (psi) std dev(psi) 182.6 105.3 89.8 108.8 32.4 182.6 Tensile Elongation at break,137.42 203.69 171.06 205.44 248.66 137.6 23° C. (%) std dev (%) 64.0230.87 19.52 32.55 10.74 64.07 Ex. 54 Ex. 55 Ex. 56 Ex. 57 Ex. 58 Ex. 59PROCESS VARIATIONS % (PP + EPR) added 100 100 100 100 0 0 downstreamupstream mixing +1 +1 +1 +1 +1 +1 downstream mixing −1 −1 +1 +1 +1 +1PROPERTIES HDT, 66 psi, ⅛ in (° F.) 225.5 230.4 238.1 233.6 235.4 234.6std dev (° F.) 8.1 0.9 0.8 1.9 2.3 3.0 HDT, 264 psi, ⅛ in (° F.) 165.5168.7 171.4 170.3 169.7 169.0 std dev (° F.) 1.7 0.9 2.3 0.8 0.8 2.6Notched Izod, 23° C. (ft-lb/in) 8.4 8.5 7.5 7.8 7.2 7.5 std dev(ft-lb/in) 0.4 0.2 0.3 0.4 0.2 0.3 Notched Izod, −30° C. (ft-lb/in) 2.72.7 2.2 2.1 2.1 2.1 std dev (ft-lb/in) 0.3 0.3 0.2 0.1 0.2 0.2 DynatupEnergy to Failure, 17.77 17.75 17.52 17.5 16.83 17.52 23° C., 7.5 mph(ft-lb) std dev (ft-lb) 0.40 0.17 0.5 0.52 0.28 0.13 Dynatup TotalEnergy, 23° C., 28.84 29.89 28.07 27.07 25.59 28.47 7.5 mph (ft-lb) stddev (ft-lb) 3.20 1.57 1.13 3.22 2.56 1.41 Dynatup Energy to Failure,15.62 15.83 17.18 16.61 13.39 16.56 −30° C., 7.5 mph (ft-lb) std dev(ft-lb) 5.38 6.89 6.80 6.12 7.66 5.44 Dynatup Total Energy, 17.88 20.6518.26 19.21 14.45 18.05 −30° C., 7.5 mph (ft-lb) std dev (ft-lb) 7.8012.27 7.37 8.76 8.49 6.66 Dynatup Energy to Failure, 17.09 20.81 15.1718.22 12.13 16.05 −30° C., 5 mph (ft-lb) std dev (ft-lb) 6.56 3.49 6.133.80 6.45 6.95 Dynatup Total Energy, 20.63 27.63 17.73 19.85 13.33 18.84−30° C., 5 mph (ft-lb) std dev (ft-lb) 9.48 8.10 9.08 5.06 8.09 9.37Flexural Modulus, 23° C., ⅛ in 215,700 218,400 225,100 220,400 220,900220,600 (psi) std dev (psi) 997 2,298 2,172 1,398 1,373 728 FlexuralStrength at Yield, 7,052 7,098 7,307 7,195 7,075 7,099 23° C., ⅛ in(psi) std dev (psi) 23 35 35 44 29 50 Tensile Strength at Yield, 4,8264,867 4,936 4,910 4,824 4,814 23° C., ⅛ in (psi) std dev (psi) 13.0 11.425.8 19.4 19.7 32.5 Tensile Strength at Break, 4,541 4,472 4,601 4,6654,607 4,575 23° C., ⅛ in (psi) std dev (psi) 67.4 105.8 88.7 62.0 60.2153.4 Tensile Elongation at break, 215.86 212.81 196.47 232.73 216.67206.02 23° C. (%) std dev (%) 26.76 33.25 33.81 9.92 18.80 80.46

EXAMPLE 60

Poly(2,6-dimethyl-1,4-phenylene ether) (16.2 weight percent, IV=0.40dL/g), homopolystyrene (20.2 weight percent),styrene-(ethylene-butylene)-styrene copolymer (3.15 weight percent), andstyrene-butadiene-styrene triblock copolymer (11.40 weight percent), andpolypropylene-graft-polystyrene copolymer (5.90 weight percent) are hadmixed in a bag and fed upstream to an extruder as described for Examples1-3. Polypropylene (33.90 weight percent), ethylene-propylene rubber(6.20 weight percent), and additionalstyrene-(ethylene-butylene)-styrene copolymer (3.15 weight percent) arepre-mixed and fed downstream at barrel 6 of the 10-barrel extruder. Theresulting composition is forced through a three-hole die to produce meltstrands, which are cooled and chopped into pellets.

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing fromessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety.

1. A method of preparing a thermoplastic composition, comprising: melt-blending a poly(arylene ether), a poly(alkenyl aromatic) resin, a hydrogenated block copolymer of an alkenyl aromatic compound and a conjugated diene, and an unhydrogenated block copolymer of an alkenyl aromatic compound and a conjugated diene to form a first intimate blend; and melt-blending a polyolefin and additional hydrogenated block copolymer with the first intimate blend to form a second intimate blend comprising the first intimate blend, the polyolefin, and the additional hydrogenated block copolymer.
 2. The method of claim 1, wherein melt-blending to form a first intimate blend comprises heating to a temperature of about 80° C. to about 400° C.
 3. The method of claim 1, wherein the melt-blending to form a first intimate blend comprises mixing with at least two mixing elements.
 4. The method of claim 1, wherein melt-blending to form a first intimate blend and melt-blending to form a second intimate blend collectively comprise mixing with a mixing energy input of at least about 0.20 kW-hr/kg.
 5. The method of claim 1, wherein the first intimate blend further comprises a polyolefin in an amount not greater than that of the polyolefin added during formation of the second intimate blend.
 6. The method of claim 1, wherein the poly(arylene ether) comprises a plurality of structural units of the formula:

wherein for each structural unit, each Q¹ is independently halogen, primary or secondary C₁-C₈ alkyl, phenyl, C₁-C₈ haloalkyl, C₁-C₈ aminoalkyl, C₁-C₈ hydrocarbonoxy, or C₂-C₈ halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms; and each Q² is independently hydrogen, halogen, primary or secondary C₁-C₈ alkyl, phenyl, C₁-C₈ haloalkyl, C₁-C₈ aminoalkyl, C₁-C₈ hydrocarbonoxy, or C₂-C₈ halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms.
 7. The method of claim 2, wherein each Q¹ is independently C₁-C₄ alkyl or phenyl, and each Q² is independently hydrogen or methyl.
 8. The method of claim 1, wherein the poly(arylene ether) has an intrinsic viscosity of about 0.2 to about 0.6 dL/g as measured in chloroform at 25° C.
 9. The method of claim 1, wherein the poly(arylene ether) comprises a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol.
 10. The method of claim 1, wherein the first intimate blend comprises the poly(arylene ether) in an amount of about 10 to about 59 weight percent, based on the total weight of the composition.
 11. The method of claim 1, wherein the poly(alkenyl aromatic) resin comprises at least 25% by weight of structural units derived from an alkenyl aromatic monomer of the formula

wherein R¹ is hydrogen, C₁-C₈ alkyl, or halogen; Z is vinyl, halogen, or C₁-C₈ alkyl; and p is 0 to
 5. 12. The method of claim 1, wherein the poly(alkenyl aromatic) resin comprises at least one poly(alkenyl aromatic) resin selected from the group consisting of atactic homopolystyrene, syndiotactic homopolystyrene, rubber-modified polystyrene, and mixtures comprising at least one of the foregoing poly(alkenyl aromatic) resins.
 13. The method of claim 1, wherein the first intimate blend comprises about 1 to about 46 weight percent poly(alkenyl aromatic) resin, based on the total weight of the composition.
 14. The method of claim 1, wherein the hydrogenated block copolymer comprises: (A) at least one block derived from an alkenyl aromatic compound having the formula

wherein R² and R³ each represent a hydrogen atom, a C₁-C₈ alkyl group, or a C₂-C₈ alkenyl group; R⁴ and R⁸ each represent a hydrogen atom, a C₁-C₈ alkyl group, a chlorine atom, or a bromine atom; and R⁵-R⁷ each independently represent a hydrogen atom, a C₁-C₈ alkyl group, or a C₂-C₈ alkenyl group, or R⁴ and R⁵ are taken together with the central aromatic ring to form a naphthyl group, or R⁵ and R⁶ are taken together with the central aromatic ring to form a naphthyl group; and (B) at least one block derived from a conjugated diene, in which the aliphatic unsaturated group content in the block (B) is reduced by hydrogenation.
 15. The method of claim 1, wherein the hydrogenated block copolymer has an alkenyl aromatic content of about 10 to about 90 weight percent.
 16. The method of claim 1, wherein the hydrogenated block copolymer has an alkenyl aromatic content of about 40 to about 90 weight percent.
 17. The method of claim 1, wherein the hydrogenated block copolymer has an alkenyl aromatic content of about 50 to about 90 weight percent.
 18. The method of preparing the thermoplastic composition of claim 1, wherein the hydrogenated block copolymer comprises a styrene-(ethylene-butylene)-styrene triblock copolymer.
 19. The method of claim 1, wherein the first intimate blend comprises about 1 to about 20 weight percent hydrogenated block copolymer, based on the total weight of the composition.
 20. The method of claim 1, wherein the wherein the unhydrogenated block copolymer comprises a styrene-butadiene diblock copolymer or a styrene-butadiene-styrene triblock copolymer.
 21. The method of claim 1, wherein the first intimate blend comprises about 1 to about 20 weight percent of the unhydrogenated block copolymer, based on the total weight of the composition.
 22. The method of claim 1, wherein the polyolefin comprises a homopolymer or copolymer having at least about 80 weight percent of units derived from polymerization of ethylene, propylene, butylene, or a mixture thereof.
 23. The method of claim 1, wherein the polyolefin is a propylene polymer comprising a homopolymer of polypropylene; or a random, graft, or block copolymer of propylene and at least one olefin selected from ethylene and C₄-C₁₀ alpha-olefins, with the proviso that the copolymer comprises at least about 80 weight percent of repeating units derived from propylene.
 24. The method of claim 1, wherein the polyolefin comprises a homopolypropylene.
 25. The method of claim 1, wherein the second intimate blend comprises about 10 to about 60 weight percent polyolefin, based on the total weight of the composition.
 26. The method of claim 1, wherein the additional hydrogenated block copolymer used to form the second intimate blend is the same as the hydrogenated block copolymer used to form the first intimate blend.
 27. The method of claim 1, wherein the additional hydrogenated block copolymer used to form the second intimate blend is different from the hydrogenated block copolymer used to form the first intimate blend.
 28. The method of claim 1, wherein the additional hydrogenated block copolymer used to form the second intimate blend is a styrene-(ethylene-butylene)-styrene triblock copolymer having a styrene content of about 50 to about 90 weight percent.
 29. The method of claim 1, wherein the amount of the additional hydrogenated block copolymer is about 1 to about 20 weight percent, based on the total weight of the composition.
 30. The method of claim 1, wherein the first intimate blend and/or the second intimate blend further comprises a polypropylene-polystyrene copolymer selected from the group consisting of graft copolymers, diblock copolymers, multiblock copolymers, radial block copolymers, and combinations comprising at least one of the foregoing polypropylene-polystyrene copolymers.
 31. The method of claim 30, wherein the polypropylene-polystyrene copolymer is a graft copolymer having a propylene polymer backbone and one or more styrene polymer grafts.
 32. The method of claim 31, wherein the polypropylene-polystyrene graft copolymer comprises about 50 to about 85 weight percent of the propylene polymer backbone and about 15 to about 50 weight percent of the styrene polymer grafts.
 33. The method of claim 30, wherein the polypropylene-polystyrene copolymer is present in an amount of about 0.5 to about 30 weight percent, based on the total weight of the composition.
 34. The method of claim 1, wherein the first intimate blend and/or the second intimate blend further comprises an ethylene/alpha-olefin elastomeric copolymer.
 35. The method of claim 34, wherein the ethylene/alpha-olefin elastomeric copolymer is a copolymer of ethylene and at least one C₃-C₁₀ alpha-olefin.
 36. The method of claim 34, wherein the ethylene/alpha-olefin elastomeric copolymer is an ethylene-butylene rubber, an ethylene-propylene rubber, or a mixture thereof.
 37. The method of claim 34, wherein the ethylene/alpha-olefin elastomeric copolymer is present in an amount of about 1 to about 20 weight percent, based on the total weight of the composition.
 38. The method of claim 1, wherein the second intimate blend further comprises at least one reinforcing filler.
 39. The method of claim 38, wherein the reinforcing filler is selected from the group consisting of glass fibers, talc, quartz fibers, carbon fibers, potassium titanate fibers, silicon carbide fibers, boron carbide fibers, gypsum fibers, aluminum oxide fibers, iron fibers, nickel fibers, copper fibers, wollastonite fibers, poly(ether ketone) fibers, polyimide benzoxazole fibers, poly(phenylene sulfide) fibers, polyester fibers, aromatic polyamide fibers, aromatic polyimide fibers, aromatic polyetherimide fibers, acrylic fibers, poly(vinyl alcohol) fibers, polytetrafluoroethylene fibers, and combinations comprising at least one of the foregoing reinforcing fillers.
 40. The method of claim 38, wherein the reinforcing filler is glass fibers.
 41. The method of claim 38, wherein the second intimate blend further comprises a graft copolymer comprising a polyolefin backbone and polar grafts formed from one or more cyclic anhydrides.
 42. The method of claim 1, further comprising blending the second intimate blend with at least one reinforcing filler.
 43. The method of claim 1, further comprising blending the second intimate blend with at least one reinforcing filler and a graft copolymer comprising a polyolefin backbone and polar grafts formed from one or more cyclic anhydrides.
 44. The method of claim 1, wherein the first intimate blend and/or the second intimate blend further comprises an additive selected from the group consisting of stabilizers, mold release agents, processing aids, flame retardants, drip retardants, nucleating agents, UV blockers, dyes, pigments, antioxidants, antistatic agents, and combinations comprising at least one of the foregoing additives.
 45. A method of preparing a thermoplastic composition, comprising: melt-blending to form a first intimate blend comprising about 10 to about 59 weight percent of a poly(arylene ether); about 1 to about 46 weight percent of a poly(alkenyl aromatic) resin; about 1 to about 20 weight percent of a hydrogenated block copolymer of alkenyl aromatic compound and a conjugated diene; and about 1 to about 20 weight percent of an unhydrogenated block copolymer of an alkenyl aromatic compound and a conjugated diene; and melt-blending about 10 to about 60 weight percent of a polyolefin and about 1 to about 20 weight percent of additional hydrogenated block copolymer with the first intimate blend to form a second intimate blend comprising the first intimate blend, about 10 to about 60 weight percent of the polyolefin, and about 1 to about 20 weight percent of additional hydrogenated block copolymer; wherein all weight percents are based on the total weight of the composition.
 46. A method of preparing a thermoplastic composition, comprising: melt-blending to form a first intimate blend comprising about 10 to about 59 weight percent of a poly(arylene ether) comprising 2,6-dimethyl-1,4-phenylene ether units, 2,3,6-trimethyl-1,4-phenylene ether units, or a combination thereof; about 1 to about 46 weight percent of polystyrene or rubber-modified polystyrene; about 1 to about 20 weight percent of a styrene-(ethylene-butylene)-styrene block copolymer having a styrene content of about 50 to about 90 weight percent; and about 1 to about 20 weight percent of a styrene-butadiene-styrene block copolymer; and melt-blending about 10 to about 60 weight percent of polypropylene, about 1 to about 20 weight percent of additional styrene-(ethylene-butylene)-styrene block copolymer having a styrene content of about 50 to about 90 weight percent, and about 1 to about 20 weight percent of ethylene-butylene rubber or ethylene-propylene rubber with the first intimate blend to form a second intimate blend comprising the first intimate blend, about 10 to about 60 weight percent of the polypropylene, about 1 to about 20 weight percent of additional styrene(ethylene-butylene)-styrene block copolymer having a styrene content of about 50 to about 90 weight percent, and about 1 to about 20 weight percent of ethylene-butylene rubber or ethylene-propylene rubber; wherein all weight percents are based on the total weight of the composition. 